Martin Wittenberg

Recent Working Papers

Testing for a common latent variable in a linear regression

We present a test of the hypothesis that a subset of the regressors are all proxying for the same latent variable. This issue will be of interest in cases where there are several correlated measures of elusive concepts such as misgovernance or corruption; in analyses where key variables such as income are not measured at all and one is forced to rely  on various proxies, e.g. in the form of an "asset index"; and where the  key regressors are badly measured and one is trying to extract a stronger signal from the regression by adding additional proxies as suggested by Lubotsky and Wittenberg (2006). We apply this test in three contexts, each characterised by a different estimation challenge arising from data limitations and show that the empirical conclusions are altered.

Keywords: measurement error, proxy variables, specification test, asset index

JEL codes: C12, C13, C52
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Industrialisation and surplus labour: A general equilibrium model of sleep, work and leisure

This paper marries a Beckerian time allocation model to a Krugman-like general equilibrium model. For certain parameter choices the model exhibits a development trap: one equilibrium is a high work, high leisure, low sleep equilibrium while another is a low work, low leisure, high sleep one.
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Restructuring of households in rural South Africa: Reflections on average household size in the Agincourt sub-district 1992-2003 (with Mark Collinson)

We analyse the Agincourt Demographic Surveillance data to try to understand the trend to smaller households that is also evident from South Africas national household surveys.
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The School Day in South Africa

This paper is a simple, descriptive piece. It uses South Africas Time Use Survey to look at what learners get up to during a typical school day. It shows that punctuality seems to be a problem and that there are systematic differences between how girls and boys spend their time.
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